The Best Actor award should actually be titled "the
best performance by an actor in a leading role." The same rules that
govern the Best Actor category apply to the Best Actress category. (See
the complete list of all Best Actor and Best Supporting Actor winners
here)

The Top Best Actor Winner:

Daniel Day-Lewis is the only actor to win three Best
Actor awards: My Left Foot (1989), There
Will Be Blood (2007), and Lincoln (2012). (His nominations
were from 1989-2012.)

There are only two actresses
(Luise Rainer and Katharine Hepburn) who have received two consecutive Best
Actress awards, as there are only two actors who have received
two consecutive Best Actor statuette wins:

In 1997, Jack Nicholson tied Walter Brennan for the
most wins (3) for a male performer (Brennan has three Best Supporting
Actor trophies, Nicholson has two for Best Actor and one for Best Supporting
Actor). The only stars to win both a Best Actor and a Best Supporting Actor (BSA) Oscar are the following:

Kevin Spacey (BA for American Beauty (1999), BSA for The Usual Suspects (1995))

Denzel Washington (BA for Training Day (2001), BSA for Glory (1989))

The Only Best Actor Tie:

In the Best Actor category, an unusual tie (the only
occurrence among male acting performances) occurred in 1931/32 between
Wallace Beery and Fredric March, for their respective performances in The Champ (1931/32) and Dr. Jekyll and Mr. Hyde (1931/32).

The Most Best Actor Oscar Nominations - Without Winning:

Peter O'Toole is the only star with eight Best Actor
Oscar nominations without a single win. His record extends 44 years,
from 1962 to 2006.

Richard Burton was nominated seven times (and never won), although his first nomination was as Best Supporting Actor for My Cousin Rachel (1952) -- his last six nominations were as Best Actor.

Oscar-Winning Actor Roles and Trends:

Biographies of remarkable, real-life individuals (military
figures or soldiers, law-and-order enforcers, historical figures) and
portrayals of the mentally ill are heavily represented among male Oscar
winners, particularly in the acting awards. It helps an actor's chances
of winning an Oscar if the character dies a tragic death during the
movie, or is slightly eccentric (or genius).

Physical and Mental Disabilities or Diseases

An overwhelming number
of actors have won (or been nominated for) the top acting (and supporting)
awards for portraying characters with physical or mental disabilities
(personality disorders, amnesia) or diseases (with handicaps, such
as blindness or muteness, tics, etc.):

Fredric March won the Best Actor Oscar for his dual,
split personality role as a respected doctor and as a fiendish
mad-man in Dr.
Jekyll and Mr. Hyde (1931/32)

Ronald Colman was nominated as Best Actor for his
role as shell-shocked amnesiac Charles Rainier in Random
Harvest (1942)

Harold Russell (real-life amputee) won the Best
Supporting Actor Oscar for his role as courageous and resourceful
returning sailor Homer Parrish in
The Best Years of Our Lives (1946) [Note: Russell
is the only performer to win two Oscars for the same performance.
In 1946, he won Best Supporting Actor and was voted an Honorary Oscar
that same year for his performance.]

Arthur Kennedy was nominated as Best Actor for his
role as veteran Larry Nevins made blind in WWII combat
in Bright
Victory (1951)

Cliff Robertson won the Best Actor Oscar for his
title role as Charly Gordon - a mentally-retarded, thirty year-old
bakery worker temporarily made a genius through surgery in Charly
(1968)

Alan Arkin was nominated as Best Actor for his role
as deaf-mute Singer in The Heart is a Lonely Hunter (1968)

Sir John Mills won the Best Supporting Actor Oscar
for his role as mute, gentle, mis-shaped village idiot
Michael in
Ryan's Daughter (1970) - he became the sole male actor to
win an Oscar for a non-speaking role

Jon Voight won the Best Actor Oscar for his role
as handicapped Luke Martin - a bitter but sensitive paraplegic
veteran paralyzed during the Vietnam War in Coming
Home (1978)

Timothy Hutton won the Best Supporting Actor Oscar
for his role as guilt-ridden, depressed teenaged Conrad Jarrett
in Ordinary
People (1980)

John Malkovich was nominated as Best Supporting
Actor for his role as blind boarder Mr. Will in Places
in the Heart (1984)

Dustin Hoffman won the Best Actor Oscar for his
role as institutionalized, ultimately loveable, autistic idiot
savant Raymond ('Ray(n)' 'Man(d)') Babbitt in Rain
Man (1988)

Daniel Day-Lewis won the Best Actor Oscar for his
role as Irish-born artist and author Christy Brown - a self-reliant,
spastic quadriplegic cerebral palsy victim who could only write
and draw with his foot in My
Left Foot (1989)

Anthony Hopkins won the Best Actor Oscar for his
role as cannibalistic, menacing, psychopathic serial psychiatrist/killer
Dr. Hannibal "Cannibal" Lecter in The
Silence of the Lambs (1991)

Al Pacino won the Best Actor Oscar for his role
as foul-mouthed, suicidal, blind (as a result of a boozing-related
accident), retired Lt. Col. Frank Slade in Scent of
a Woman (1992)

Tom Hanks won the Best Actor Oscar for his role
as AIDS-infected corporate attorney and victim Andrew Beckett in Philadelphia
(1993) - Hanks' 1994 acceptance speech
for his Best Actor Oscar win for Philadelphia (1993) directly
inspired the homosexuality-themed film In & Out (1997),
about an outed English literature teacher (Kevin Kline) in an
Indiana town when one of his former students (Matt Dillon) thanked
him at the Academy Awards and mentioned he was gay

Tom Hanks won the Best Actor Oscar again for his
title role as Forrest Gump, a good-hearted, naive, eccentric,
dim-witted protagonist (an idiot-savant) in Forrest
Gump (1994)

Geoffrey Rush won the Best Actor Oscar for his role
as talented but agonizingly-troubled, mentally-disabled Australian
concert pianist David Helfgott who suffered a crippling nervous
breakdown in Shine
(1996)

Jack Nicholson won the Best Actor Oscar for his
role as rich, bigoted, obsessive-compulsive romance novelist Melvin
Udall living in New York in As
Good As It Gets (1997)

Geoffrey Rush was also nominated as Best Actor
for his role as sexually-crazed French novelist Marquis de Sade
in Quills
(2000)

Jamie Foxx won the Best Actor Oscar for his role
as legendary blues singer and blind pianist Ray Charles in Ray
(2004)

Forest Whitaker won the Best Actor Oscar for his
role as brutal, infamous, genocidal Ugandan dictator Idi Amin in
The Last King of Scotland (2006)

Colin Firth won the Best Actor Oscar for his role
as stuttering monarch George VI in The King's Speech (2010)

Eddie Redmayne won the Best Actor Oscar for his
role as ALS-diagnosed physicist Stephen Hawking in The Theory of
Everything (2014)

Alcoholics

And a number of other actors have won Oscar
awards (or been nominated) for portraying alcoholic characters:

Lionel Barrymore won the Best Actor Oscar for his
role as dissolute and drunken lawyer Stephen Ashe (co-star Norma
Shearer's father) in A
Free Soul (1930/31)

Van Heflin won the Best Supporting Actor Oscar for
his role as Shakespeare-quoting, alcoholic confidant Jeff Hartnett
who befriended gangster co-star Robert Taylor in
Johnny Eager (1942)

Ray Milland won the Best Actor Oscar for his role
as whiskey-soaked, boozing, writer's blocked Don Birnam in The
Lost Weekend (1945)

Fredric March won Best Actor for his role as anguished,
middle-aged, alcoholic banking executive - and returning war veteran
and ex-sergeant Al Stephenson in The
Best Years of Our Lives (1946)

James Mason was nominated as Best Actor for his
role as ruined, alcoholic actor Norman Maine in A
Star Is Born (1954)

Jack Lemmon was nominated as Best Actor for his
role as alcoholic advertising man Joe Clay in Days
of Wine and Roses (1962)

Dudley Moore was nominated as Best Actor for his
role as drunk, spoiled, amiable and millionaire-rich playboy -
title character Arthur Bach in Arthur
(1981)

Paul Newman was nominated as Best Actor for his
role as alcoholic, ambulance-chasing, Boston trial lawyer Frank
P. Galvin in The
Verdict (1982)

Robert Duvall won Best Actor for his role as ex-drinking,
ex-country/western music star Mac Sledge in Tender
Mercies (1983)
Note:
in 1983, all five Best Actor nominees played drunks of one sort or
another (two were nominated for the film The Dresser (1983),
Albert Finney and Tom Courtenay)

Albert Finney was nominated as Best Actor for his
role as self-destructive alcoholic Geoffrey Firmin drinking himself
to death in the shadow of a Mexican volcano in Under
the Volcano (1984)

Nicolas Cage won the Best Actor Oscar for his role
as failed, Hollywood scriptwriter and fatally-destructive, genial,
but suicidal alcoholic Ben Sanderson in Leaving
Las Vegas (1995)

Robert Duvall was nominated as Best Actor for his
role as Texas Pentecostal preacher Eulis ("Sonny") Dewey
who became 'The Apostle' of God in Louisiana to escape his past
in The
Apostle (1997)

James Coburn won the Best Supporting Actor Oscar
for his role as Nick Nolte's tyrannical, abusive and alcoholic
father Glen "Pop" Whitehouse in Affliction (1998)

Jeff Bridges won the Best Actor Oscar for his role
as broken-down, aging, boozy country-music singer Bad Blake in Crazy
Heart (2009)

Denzel Washington was nominated as Best Actor for
his role as tragic, heroic, and addicted boozy airline
pilot Whip Whitaker in Flight (2012)

Homosexual Roles

Some straight actors have been nominated
(and often won) for homosexual roles:

Peter Finch received his first Best Actor nomination
(without winning) for his role as middle-aged, homosexual Jewish Dr.
Daniel Hirsh involved
in a three-sided love story in Sunday,
Bloody Sunday (1971)

William Hurt won Best Actor for his role as imprisoned,
flamboyant gay South American Luis Molina in Kiss of the
Spider Woman (1985)

Tom Hanks won Best Actor for his role as dying AIDS patient Andrew Beckett in Philadelphia (1993)

Sean Penn won the Best Actor Oscar for his role
as openly pioneering San Francisco gay camera store owner Harvey
Milk who successfully was serving in public office as mayoral aide
when he was assassinated, in Milk (2008)

Mediocre or Compensatory Oscar Wins:

Oscar victories for Best Actor haven't always been
for the stars' best work either, but have often been an effort to
right past injustices, or retroactively for an entire body of work:

56 year-old Ronald Colman's late win as Best Actor
for A Double Life (1947) - a tribute to his entire silent and
sound film career

Paul Newman's sole Oscar win for reprising his "Hustler"
role as pool player Eddie Felson in The Color of Money (1986)
was a dubious honor - it really represented praise for his entire
career's work, for his colorful non-conformist roles in The
Hustler (1961), Hud (1963),
and Cool Hand Luke (1967)

A late-career win was also given to Al Pacino for
Scent of a Woman (1992) for his role as a blind, suicidal
ex-Army officer, after seven acting nominations, including four
Best Actor losses for Serpico
(1973),
The Godfather, Part II (1974), Dog Day Afternoon (1975),
and And Justice For All (1979), and three other Best Supporting
Actor losses ( The
Godfather (1972), Dick
Tracy (1990) and Glengarry Glen Ross (1992))

Sean Connery won Best Supporting Actor for The
Untouchables (1987), but he should have been nominated (and won)
for earlier, more deserving performances in The Hill (1965),
The Molly Maguires (1970), or The Man Who Would Be King
(1975)

John Gielgud won Best Supporting Actor for his performance
as the butler in Arthur (1981), but he should have won instead
for either Julius Caesar (1953), Richard III (1955) or
Becket (1964)

A seriously-ill, 76 year-old Henry Fonda won Best
Actor for On Golden Pond (1981), despite the brilliant performance
of Burt Lancaster in Atlantic City (1981). Fonda should have
won years earlier for any number of performances, including
The Grapes of Wrath (1940) or The Ox-Bow
Incident (1943)

Heath Ledger - nominated and winning the Best Supporting Actor Oscar for The Dark Knight (2008) posthumously - the second performer to win posthumously

The Most Best Actor Nominations for a Single Film:

The film with the most Best Actor nominations (3)
was Mutiny on the Bounty (1935), for Clark
Gable, Franchot Tone, and Charles Laughton. It was the first film to have three acting nominations,
and the first film to have three co-performers competing against each other
in the same category - as Best Actor.

African-American (or Black) Notables:

There have only been twenty African-American
(or black) nominations for Best Actor, divided amongst thirteen different
performers. Four actors (Poitier, Freeman, Washington and Smith)
have been nominated twice (or more) for the top award. Some regard
Denzel Washington as the first African-American performer
to win Best Actor -- because previous Oscar-winner Sidney Poitier
was of Bahamas descent:

In total, there have only been 23 different African-American
(or black) performers nominated for the top award (either Best Actor
or Best Actress).
Only fourteen awards have been won by African-Americans (or
blacks) in both lead and supporting categories (four Best Actor, one
Best Actress, four Best Supporting Actor, and five Best Supporting
Actress). Only five black performers have won the Oscar in the lead
category (four Best Actor, one Best Actress).

Only four African-American
actors have won the Best Actor Oscar:

Sidney Poitier for Lilies of the Field (1963)

Denzel Washington for Training Day (2001)

Jamie Foxx for Ray (2004)

Forest Whitaker for The Last King of Scotland (2006)

Five of the 20 acting nominations in 2004 and 2006 were
African-American nominees. This bested the record of three nominated
blacks that occurred in three different years (2001, 1985, and 1972):

2006

2004

Will Smith, The Pursuit of Happyness
Forest Whitaker, The Last King of Scotland
Djimon Honsou, Blood Diamond
Eddie Murphy, Dreamgirls
Jennifer Hudson, Dreamgirls

1972: Diana Ross for Lady Sings the Blues,
and Cicely Tyson and Paul Winfield for Sounder

Jamie Foxx also set a record for being the first black
to debut as a nominee in two categories in the same year, lead
and supporting, for Ray (2004) and Collateral (2004).

Denzel Washington is the only black actor nominated
six times for Best Actor or Best Supporting Actor. With his
nomination for Flight (2012), he became the most nominated
African-American actor in Academy history. He is the only black
actor to have won two competitive Oscars (as Best Supporting Actor
for Glory
(1989) and
as Best Actor for Training
Day (2001)).

Two African-American actors have been nominated
for Best Actor in the same year, numerous times:

Year

Best Actor Nominees

2006

Will Smith for The Pursuit of Happyness (2006),
Forest Whitaker for The Last King of Scotland (2006)

2004

Don Cheadle for Hotel Rwanda (2004), Jamie
Foxx for Ray (2004)

2001

Will Smith for Ali (2001), Denzel Washington
for Training Day (2001)

Morgan Freeman's Best Supporting Actor
win for Million Dollar Baby (2004), paired with Jamie Foxx's
Best Actor win for Ray (2004), was the first
time that African-American actors won in their respective categories
in the same year.

In three instances, African-Americans have won
two of the four acting prizes:

2006: Forest Whitaker for The Last King of Scotland,
Jennifer Hudson for Dreamgirls

There have been only a few Best Actor Oscar wins by
ethnic/other minority (or non-English) performers:

French actor Jean Dujardin won Best
Actor for The Artist (2011) - he was the first French
actor to win the Best Actor Oscar

Italian actor Roberto Benigni won the Best Actor
Oscar for Life is Beautiful (1998)- he
was the first male actor to win an
Oscar for a foreign-language film (his Best Actor Oscar win
was only the second time a nominee won an acting Oscar for a
foreign language film role - the earlier winner was Sophia Loren)

Ben Kingsley, with half-Indian (birth name Krishna
Bhanji) and half-English descent, won the Best Actor Oscar for Gandhi
(1982) - he became the first South Asian performer to achieve
such a feat

Puerto Rican-born Jose Ferrer won the Best Actor
Oscar for his role in Cyrano de Bergerac (1950)

Australian actor Hugh Jackman was nominated as Best
Actor for Les Miserables (2012)

Mexican-born actor
Demián
Bichir was nominated as Best Actor for A Better Life (2011)

Ben Kingsley was nominated as Best Actor for House
of Sand and Fog (2003)

Spanish/Latino actor Javier Bardem was nominated as Best
Actor for Before Night Falls (2000) and for Biutiful (2010) - he was the first Best Actor nominee for a fully Spanish-language role

Australian actor Geoffrey Rush was nominated as Best Actor for Shine (1996) (win) and Quills (2000) - Geoffrey Rush became the first Australian actor
to win Best Actor (for the role of the mad pianist in Shine (1996))
since Peter Finch won posthumously for Network
(1976)

Italian actor Massimo Troisi was nominated as Best Actor for The Postman (Il Postino) (1995)

French actor Gerard Depardieu was nominated as Best Actor for Cyrano de Bergerac (1990)

Swedish actor Max Von Sydow was nominated as Best Actor for Pelle the Conqueror (1988)

Mexican-American Edward James Olmos was nominated
as Best Actor for Stand and Deliver (1988)

Italian actor Marcello Mastroianni was nominated as Best Actor for Dark Eyes (1987)

Italian actor Marcello Mastroianni was nominated as Best Actor for A Special Day (1977)

Italian actor Giancarlo Giannini was nominated as Best Actor for Seven Beauties (1976)

Mexican-born Anthony Quinn was nominated twice as
Best Actor for Wild Is the Wind (1957) and Zorba the Greek
(1964)

Puerto Rican-born Jose Ferrer was nominated as Best
Actor for Moulin Rouge (1952)

Note: In 1985, all ten of the Best Actor/Actress
nominees were American-born - the first time in Oscar history. Also, in 1964 and in 2007, all four winners of the performance/acting Oscars were non-Americans.

Multiple Nominations for the Same Character -- The Most Oscar-Friendly Role:

The character of Henry VIII has the most acting nominations
(three) and is the most Oscar-friendly role:

Charles Laughton as Henry VIII in The Private
Life of Henry VIII (1933) - the only winner of the three - a Best Actor Oscar

Robert Shaw as Henry VIII in A Man for All Seasons
(1966) - nominated as Best Supporting Actor

Richard Burton as Henry VIII in Anne of the Thousand
Days (1969) - nominated as Best Actor

Only two nominees in Oscar history have been nominated for playing the role of a real-life Oscar nominee: Cate Blanchett as Best Supporting Actress (win) for playing the role of Katharine Hepburn in The Aviator (2004), and Robert Downey, Jr. nominated as Best Actor for the title role of Oscar nominee Charlie Chaplin in Chaplin (1992).

Multiple Nominations for the Same Character:

Four actors have been nominated twice for playing
the same character in two different films (wins are marked with an *):

Bing Crosby as Father Charles "Chuck" O'Malley in Going
My Way (1944)* and The Bells of St. Mary's (1945)

Only one actress has ever received two nominations for playing the same character in two different films:

Cate Blanchett became the fifth performer to draw mentions for the same role (Queen Elizabeth I) in two different films: Best Actress for Elizabeth: The Golden Age (2007) and Best Actress for Elizabeth (1998)

Multiple Nominations:

After 1929/30, an actor could not receive more than
one nomination per category. In 1944, the rules permitted Barry Fitzgerald
to be nominated for Best Actor and Best Supporting Actor (which he won)
for the same performance - Father Fitzgibbon in Going My Way
(1944). Subsequently, new rules have prevented this from re-occurring,
although an actor may still be nominated in both categories for two
different roles. (See the Best Supporting Actor and Best
Supporting Actress pages for further information on double nominees.)

Barry Fitzgerald is the only actor to be nominated
for both Best Actor and Best Supporting Actor for the same
character (or performance) in the same year. Since then,
two other male performers have been double-nominated in a single
year (wins are marked with *) - Pacino was the first actor
to be nominated for Best Actor and Best Supporting Actor in two different roles;
the second actor in Oscar history to do so was Jamie Foxx in 2004:

Barry Fitzgerald (Best Actor for Going My Way
(1944)* and Best Supporting Actor for Going My Way (1944))

Al Pacino (Best Actor for Scent of a Woman (1992)*
and Best Supporting Actor for Glengarry Glen Ross (1992))

Emil Jannings was the only performer to win the
Best Actor award for his performances in two films in the same year: The
Last Command (1927/28) and The Way of All Flesh (1927/28) -
he was the very first actor to win the Academy Award for
Best Actor; the Switzerland-born actor was the first non-American
to win the award, which was presented to him a month before the
ceremony.

Winning Co-Stars: Best Actor and Best
Actress in the Same Film:

Seven films have won in both the leading actor and leading
actress categories:

Not a single actor has ever won the Best Actor
Oscar for a feature film debut. A few of those below had very small debuting roles before a substantial film appearance. Others have
received nominations for Best Actor for their debut role (a sampling):

Ben Kingsley in Gandhi (1982) (win) (he had a bit role in his feature film debut, Fear is the Key (1972))

Geoffrey Rush in Shine (1997) (win) (he had a bit role in a few earlier films, including Hoodwink (1981))

Reprising an Acclaimed Stage Role:

Six Best Actor winners won the Oscar for an acclaimed
stage role that they reprised on the screen. Those with an asterisk (*) won both a Best Actor Oscar and a Tony Award for musical roles they had created on stage:

The World According to Garp (1982), The Big Chill (1983), The Natural (1984)

William Hurt (1985-1987)

Kiss of the Spider Woman (1985)*, Children of a Lesser God (1986), Broadcast News (1987)

Russell Crowe (1999-2001)

The Insider (1999), Gladiator
(2000)*, A Beautiful Mind (2001)

Renee Zellweger (2001-2003)

Bridget Jones's Diary (2001), Chicago (2002), Cold Mountain (2003)*

Longest Time Period Between First and Last Nomination/Win:

48 years - Katharine Hepburn was first nominated
and won Best Actress for Morning Glory (1932/33) and then 48
years later was nominated and won Best Actress for On Golden Pond
(1981) - her fourth (and last) Oscar win!

46 years - Alan Arkin was nominated as Best Actor
for The Russians are Coming, The Russians are Coming! (1966) and
then two years later as Best Actor for The
Heart is a Lonely Hunter (1968). Then, there was a long gap
- 38 years later, after which he won Best Supporting Actor for Little
Miss Sunshine (2006). He topped that with another six year
wait for another Best Supporting Actor nomination for Argo (2012).

41 years - Henry Fonda was first nominated in 1940
as Best Actor for The Grapes Of Wrath (1940),
and wasn't nominated again until 41 years later - when he won his
sole Oscar (Best Actor) for On Golden Pond
(1981)

40 years - Mickey Rooney was first nominated as
Best Actor for Babes in Arms (1939), then as Best Actor for
The Human Comedy (1943), then as Best Supporting Actor for
The Bold and the Brave (1956), and then as Best Supporting
Actor for The Black Stallion (1979), 40 years later, but he
didn't ever win!

39 years - Jack Palance was
nominated as Best Supporting Actor for Sudden Fear (1952) and
then as Best Supporting Actor for Shane (1953)
- it was a time span of 39 years from his first nomination to his
eventual victory as Best Supporting Actor for City Slickers (1991)!

38 years - Helen Hayes had
to wait 38 years between her only Oscar nominations (both wins), Best
Actress for The Sin of Madelon Claudet (1931/32), and Best
Supporting Actress for Airport (1970)

37 years - Albert Finney was
first nominated as Best Actor for Tom Jones (1963) and then
received three more nominations for Best Actor: for Murder on the
Orient Express (1974), The Dresser (1983), and Under
the Volcano (1984) -- 37 years after his first nomination, he
received his fifth and final Oscar nomination for Best Supporting
Actor for Erin Brockovich (2000) - he never won!

Longest Gap Between First Nomination and First Winning
Film:

41 years - Henry Fonda was
first nominated in 1940 as Best Actor for The Grapes Of Wrath (1940),
and didn't win an acting award (Best Actor) until 41 years later for
On Golden Pond (1981),
and these were his only two career acting nominations (Note: Fonda
did receive a producing Best Picture nomination for 12
Angry Men (1957))

32 years - Geraldine Page was first nominated in
1953 as Best Supporting Actress for Hondo (1953), and won Best
Actress for A Trip to Bountiful (1985), 32 years later; she was the only actress with seven unsuccessful nominations (in both categories) before finally winning Best Actress with nomination # 8

28 years - Paul Newman was first nominated in 1958
as Best Actor for Cat on a Hot Tin Roof (1958),
and won Best Actor for The Color of Money (1986), 28 years
later; he was the only actor with six unsuccessful Best Actor nominations before finally winning Best Actor with nomination # 7 - and he later added another nomination as Best Actor for Nobody's Fool (1994), and his first Best Supporting Actor nomination also came later for Road to Perdition (2002)

25 years - Shirley MacLaine was first nominated in
1958 as Best Actress for Some Came Running (1958), and won
Best Actress for Terms of Endearment (1983),
25 years later

20 years - Al Pacino was first nominated in 1972
as Best Supporting Actor for The Godfather (1972),
and won Best Actor for Scent of a Woman (1992), 20 years later

20 years - John Wayne was first nominated in 1949
as Best Actor for Sands of Iwo Jima (1949), and won Best Actor
for True Grit (1969), 20 years later

18 years - Ronald Colman was first nominated in 1929/30
as Best Actor for Bulldog Drummond (1929/30), and won Best
Actor for A Double Life (1947), 18 years later

17 years - Gregory Peck was first nominated in 1945
as Best Actor for The Keys of the Kingdom (1945), and won Best
Actor for To Kill a Mockingbird (1962),
17 years later

14 years - Susan Sarandon was first nominated in
1981 as Best Actress for Atlantic City (1981), and won Best
Actress for Dead Man Walking (1995), 14 years later

Anthony Hopkins had the shortest screen time for his Best Actor Oscar win - as Hannibal "Cannibal"
Lecter in Silence of the Lambs (1991)
- supposedly 16 minutes of screen time

Only Non-Human Best Actor-Nominated Performance:

Jeff Bridges as the alien 'Starman' in Starman
(1984)

Directors Directing Themselves to a Best Actor
Oscar or Nomination:

There are only two actors/performers that have directed themselves to an Oscar-winning Best Actor Oscar:

British actor Laurence Olivier as the title character in Hamlet (1948, UK) - Olivier became the first individual to win both an acting Oscar and Best Picture Oscar (as producer) - this time for the same film

Italian actor Roberto Benigni as Guido in Life is Beautiful (1998, It.)

Many actors have directed themselves to Best Actor Oscar nominations, most prominently:

Michael Douglas became the second individual to win both an acting Oscar and Best Picture Oscar, this time for different films: Best Picture (One Flew Over the Cuckoo's Nest (1975)) and Best Actor (Wall Street (1987)).

Winning Performances Portraying Royalty:

Charles Laughton, Best Actor as King Henry VIII in The Private Life of Henry VIII (1932/33)

Paul Newman, Best Actor for The Color of Money
(1986), and Joanne Woodward, Best Actress for TheThree
Faces of Eve (1957). [Note: They were married in 1958,
prior to Woodward receiving 1957's Best Actress Award.] Newman
also directed Woodward to her second Best Actress nomination
for his Best Picture-nominated film Rachel,
Rachel (1968).

Catherine Zeta-Jones, Best Supporting Actress for
Chicago (2002), and husband Michael Douglas, Best Actor for
Wall Street (1987)[Note: The couple
were not married until the year 2000.]

There are others (girlfriend/boyfriend, or unmarried companions) who are close
to (or have achieved) the same milestone:

Spencer Tracy, Best Actor and Katharine Hepburn, Best Actress for Guess Who's Coming to Dinner (1967)

Diane Keaton, Best Actress winner for Best Director-winning Woody Allen's Annie Hall (1977) - although they were romantically linked, they never married

Amy Madigan, Best Supporting Actress for Twice
in a Lifetime (1985), and Ed Harris, nominated four times
(1995, 1998, 2000, 2002) [Note: Harris directed himself to
a Best Actor nomination for Pollock (2000).]

Susan Sarandon, Best Actress for Dead Man Walking
(1995) (directed by her Best Director-nominated husband (unofficial
live-in) Tim Robbins); Robbins won Best Supporting Actor for Mystic
River (2003); earlier, Sarandon was married to Chris Sarandon,
nominated for Best Supporting Actor for Dog Day Afternoon (1975)

Six years (and 310 days) Shirley Temple was the
youngest performer to win an Academy Award when she won an unofficial
honorary 'juvenile' Academy Award statuette in 1934, presented
on February 27, 1935.

94 years (and 341 days) Eli Wallach was the oldest
male performer to receive an honorary statuette in 2010, presented
on November 13, 2010.

85 years (and 215 days) Myrna Loy was the oldest
female performer to receive an honorary statuette in 1990,
presented on March 25, 1991.